Store capabilities of monitored server

Checking the version number in various places in the code gets confusing.
It's better to check the version in one place and record the relevant data.

server/modules/monitor/mariadbmon/cluster_discovery.cc

@@ -654,7 +654,7 @@ void MariaDBMonitor::assign_slave_and_relay_master(MariaDBServer* start_node)
         }
         // If the node is a binlog relay, remove any slave bits that may have been set.
         // Relay master bit can stay.
-        if (parent->m_version == MariaDBServer::version::BINLOG_ROUTER)
+        if (parent->m_srv_type == MariaDBServer::server_type::BINLOG_ROUTER)
         {
             parent->clear_status(SERVER_SLAVE);
         }